Fungalpedia – Note 180, Phragmothyrites (Fossil Fungi)

 

Phragmothyrites W.N. Edwards.

Citation when using this data: Saxena RK & Hyde KD. 2024 (in prep) – Fungalpedia, Fossil Fungi. 

Index Fungorum, Facesoffungi, MycoBank, GenBank, Fig. 1

Classification: Microthyriaceae, Microthyriales, Dothideomycetes, Ascomycota, Fossil Fungi.

The monotypic fossil genus, Phragmothyrites, was described by Edwards (1922) from the Eocene (56–34 mya) sediments of Mull, Scotland. Edwards (1922) stated that these fossil forms belong to the Microthyriaceae, the exact position of which is uncertain, but appears to be most closely related to Phragmothyrium as defined by Von Höhnel (1912). This diagnosis was emended by Kar and Saxena (1976), as follows: No free hyphae; ascostromata subcircular-circular, dimidiate, nonostiolate; hyphae radially arranged, interconnected to form pseudoparenchymatous cells; central cells ± squarishsubcircular, outer cells elongated, may be setose at margin and thickened. Cells with or without pores; generally, cells in the middle region are more porates than those in the outer region. 

The generic diagnosis was further amended by Kalgutkar & Jansonius (2000) as follows: Ascomata are subcircular to circular, astomate, with radially arranged hyphae that laterally interconnect to form a pseudoparenchymatous tissue. Hyphal cells are uniform in shape or size or show various developments in different regions of the ascoma, such as elongated rectangular or isodiametric. Central cells, or cells in the immediate central area, maybe cubical, hexagonal, or subcircular; however, never developed into a circular region of thick-walled isodiametric cells in the central area of the ascoma (as is characteristic of Microthyriacites). There are 23 records in Index Fungorum (2023) under this genus.

Type species: Phragmothyrites eocenicus W.N. Edwards

 

 

Figure 1 – Phragmothyrites eocenicus. Scale bar = 60 μm. Redrawn from Edwards (1922).

 

References

Edwards WN. 1922 – An Eocene microthyriaceous fungus from Mull, Scotland. Transactions of the British Mycological Society 8, 66–72.

Höhnel FV. 1912 – Fragmente zur Mykologie, Sitzungsberichte der Akademie der Wissenschaften mathematisch-naturwissenschaftliche Klasse 119, 877–958.

Kalgutkar RM, Jansonius J. 2000 – Synopsis of fungal spores, mycelia and fructifications. AASP Contribution Series 39, 1–423. 

Kar RK, Saxena RK. 1976 – Algal and fungal microfossils from Matanomadh Formation (Palaeocene), Kutch, India. Palaeobotanist 23, 1–15.

 

Entry by

Ramesh K. Saxena, Birbal Sahni Institute of Palaeosciences, Lucknow, India

 

(Edited by Kevin D. Hyde, Samaneh Chaharmiri-Dokhaharani, & Achala R. Rathnayaka)

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